


Under the Sea

by TheEarlyKat



Category: Free!
Genre: Gen, Marine Biology AU, Merman!AU
Language: English
Status: In-Progress
Published: 2013-11-01
Updated: 2013-11-20
Packaged: 2017-12-31 05:15:06
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,150
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1027654
Author URL: https://archiveofourown.org/users/TheEarlyKat/pseuds/TheEarlyKat
Summary: <blockquote class="userstuff">
              <p>Rei an Nagisa count more than just seals in their marine biology lab.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

  * Inspired by [Marine Biology AU](https://archiveofourown.org/external_works/30098) by Niuniente. 



> It's another inspired fic, this time from Niuiente's marine biology au. This is also my first Free! fanfiction, so I did my best. I'm thinking of making this a series, but because of NaNoWriMo, the updates for this will be very slow to come. Please enjoy anyway!

“We’re going to be doing something different today.” Nagisa took his eyes off the posters of local fish and crustacean migratory patterns and turned his limited attention to the professor as she stepped into the room. “I know for today’s lab we were scheduled to head down to the mudflats, but we’ve been contacted by a large fishery downtown. While it’s a little out of the way, we can still stop by the flats, but we’ll have to take a closer look at the ecosystem and meiofauna communities another day.”

There were no groans of protest, though Nagisa felt a pout cross his face at the news. While the several students that had forgotten to bring their hip waders to class, he sighed in annoyance. He had been looking forward to splashing his way through the thick mud and chasing the worms and digging up the clams that lived there. He wanted to poke at the crabs and flick the globs of mud sticking to his fingers at Rei. 

“The fishery has been experiencing unusually low catch rates for the season and want to determine that it’s not over-fishing or human pollution that’s causing it. So, we’ll be looking for and counting nearby seal and seabird populations.” The professor pulled out a tub from under her desk and handed each student a clipboard and a pair of binoculars as they headed out of the lab room. Nagisa clutched his tightly, a grin spreading across his face. Seals were much more interesting than crabs. 

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“Twenty-one, twenty-two…” the blond marked the number in a column on the worksheet with one hand as he stabilized the binoculars with the other. The heavy metal object bumped against his nose as a large wave smacked against the side of the small research boat. Behind him, he could hear the professor explain to the others the differences between herring and Bonaparte gulls. 

Nagisa searched the calm bay waters for another group of seals. He turned, the magnified view of the rocks turning to a close up of the side of the boat before landing on Rei. Nagisa could see that his glasses were slightly skewed as the taller man leaned over the railing while counting as carefully as he could. 

Nagisa tapped his shoulder and laughed. “You’ll fall into the water if you lean to too far over!”

Rei, after wheeling and stumbling back against the cabin of the boast, gave the shorter man a wary glance. “I’ll fall if you push me.”

The blond pouted. “I didn’t push you to make you fall in. I did it to give you an example.”

“That’s a dangerous example!”

“It would be funny, though. Don’t you think? Rei all wet…and covered in seaweed.”

Rei turned up his nose and crossed his arms. “It wouldn’t be beautiful, so don’t push me. Or even think of pushing me.” He glanced at the water, blue eyes watching the sunset turn the ocean all shades of blues and grays. The sky was filled with color as it blossomed with reds and purples. “It should be time to head back soon.”

“I don’t want to go yet,” Nagisa whined. “It’s so nice out here.”

Rei nodded. “There is one last rock outcropping the professor wanted us to check out. I’ll take one side if you take the other.”

The blond raised his binoculars in answer as the boat hummed its way across the water to a small pile of rocks. More were hidden under the high tide, and the boat carefully slipped around the obstacles. 

“How many did you count?”

“Six.”

“Rei, I think you need new glasses. I see seven on your side and I don’t even need the binoculars to see them all.”

“Count on your own side!”

“I will, I will! Just…yeah, see! Seven. Count them again.” Nagisa pointed to the cluster of furry bodies crowding the minimal shore. Off to the side laid a single animal.

“That’s not a seal, which is why I didn’t count it.”

“Not a seal?” Nagisa asked.

Rei pointed. “It doesn’t have fur or even an coloring like the seals, and its flippers are melded together and not webbed.” He pulled his hand back and tapped his chin. “I’d say it looks like a fluke, actually.”

“A shark, maybe?”

“Not a shark. It’s a horizontal fluke, not vertical. More likely it’s a dolphin.”

Nagisa’s eyes widened and he raised the binoculars to his eyes again. “It’s not moving and if it’s just there…do you think it’s…dead?”

“It might just be,” Rei sighed. “We should see if we collect it. I’ll get a hold of the professor.” Nagisa nodded and in a minute he felt the boat rock and slowly turn in the direction of the rocks. A furry head looked up and the seal barked, alerting the others of the incoming intruder. The animals returned the warning and slipped off the rocks, and Nagisa focused again on the dolphin. 

“Where’d it go?”

He dropped the binoculars and scoured the rocks with his eyes. The boat hadn’t switched sides. The dolphin should have been there. Unless one of the seals had jostled it…  
There was a series of bubbles and gray blubber broke the surface of the water. Nagisa kept his eyes on it this time, and his jaw dropped when it disappeared again only for a human head to surface in its place. A hand – a human hand – swept back black hair from its eyes. 

“It’s unusual for a mammal like that to be caught in the tides here.” Nagisa jumped at the sound of the professor as Rei came back with her. He was able to catch the flukes of the man to slap the water as it dived off before she leaned over the railing. “Where did you say you saw it?”

“Ah, over there – but, it looks like it disappeared…what happened to it?”

Nagisa felt the man’s eyes on him and he tried to smile. “A seal knocked it off when they jumped into the water. I couldn’t tell where it went after that. Sorry.”

The professor shrugged, but a frown pulled at her mouth. “That’s a shame. We might have learned something and maybe found out where it came from. But what can we do now?” She walked off to gather the rest of the class and wrap the day up. Rei went to follow, but the blond grabbed his sleeve and pulled him back. 

“That wasn’t a dolphin, Rei.”

“No? Was it really a shark?”

Nagisa shook his head. “You can’t say I’m making it up, because I’m not. You have to believe me, okay?”

Rei chuckled. “Are you going to tell me it was really a mermaid?”

“Merman.”

“Excuse me?”

Nagisa sighed. “It was a merman. It had a human upper body and a dolphin tail – Rei you said you would believe me!”

“I thought you would say it came back to life, not that it was an impossible life form. Maybe you just thought you saw the…merman.”

“I didn’t think I saw I, I did see it! I’ll show you. I don’t know how,” he added as Rei glanced at him from over the rim of his glasses, “but I’ll find a way. Maybe we’ll make a great discovery and we’ll be famous and get awards and be on television!”

Rei shook his head and headed towards the other students as the boat turned for the docks. Nagisa glanced over more at the water and bit his lip. He was certain he had seen the raven-haired merman. But how would he find him again?


	2. Chapter 2

**Summary for the Chapter:**

> Nagisa wants to fin the mermen. Rei just wants to have a nice weekend.

Rei finished reading the paragraph aloud and sat down in his seat again, nodding at his professor as she began to write down the topics for the day’s discussion. His eyes flickered towards the laptop Nagisa typed furiously at. The same typing that had distracted him many times while trying to complete the assignment he had been given without looking like a fool. But not that he had finished, he chanced a peek at what had kept the other so interested.

“Again?” he whispered, though he had no idea why he should shocked anymore. Filling the screen were images of men and woman, their upper torso’s bare while their lower halves were covered in scales and fins. 

“Yes, again,” Nagisa answered matter-of-factly. “Gotta do my research for when we find them again.

“We are not going to find them again. They are not real, and since they do not exists, you could not have seen them and therefore we won’t be going out again.”  
“Does someone want to keep staying over?”

Rei looked at Nagisa, blue eyes wide behind his glasses. Nagisa raised an eyebrow at him, but the smirk he flashed was anything but questioning. Rei felt his face grow warm and he looked away. “Bribing me will not prove that mermen exist.”

“So, you’re saying you want to stop coming over? And you want to stop…everything else?” he added, singing. He chuckled as Rei’s face flushed red. 

“Mr. Ryuzakai and Hazuki!” the professor scolded. “Is there something you two would like to tell the class?”

“Yes!” Nagisa chirped. “Are mermaids real?”

The professor sputtered. “T-this is a literate class, not a mythology one. Please discuss those matters in the appropriate lectures.” She turned back to the board, hushing the several giggled that echoed about the room.  
Rei cleaned his glasses, wiping the lenses off on his shirt in an attempt to keep his eyes off both Nagisa and the frustrated professor. Still, the blond leaned over from his desk to whisper, “I’ll be in the dining hall at noon if you want to come. Which you will.” 

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Rei fixed his glasses as Nagisa passed him the map of the bay. “This is where we were last week,” the darker haired man said, placing a finger on a sheltered area off to the east. “But that doesn’t mean those…ah, mermen,” Rei coughed out at a prompting look for the blond “,are. If we take closer look at the inlets and think about the terrain and other organisms, they should actually be found more often in open water.” He pressed a finger to his lips. “Unless their habits are different from that of more intelligent marine mammals or they have different preferences of habitat or needs.”

“Well if I was living in the ocean I’d want to stay somewhere safe,” Nagisa said. “Like here!” He took Rei’s hand and guided his pointed finger back to the first point. 

“It does have access to open water,” Rei agreed. “And we know what kinds of other animals live there and there’s enough diversity to suggest it’s possible to hold such creatures as these. I just think there’s too much traffic and human involvement for them to stay hidden. With so many docks and factories, how have they not been spotted before?”

“I guess we’ll just have to search around ourselves,” Nagisa sighed.

Rei raised an eyebrow at the breath. He was smiling, his eyes glittering with everything but the tiredness a sigh would suggest. Worry knotted in his stomach and he had to swallow around a lump in his throat when he asked, “And how would we do that if we have no way of getting there?”

“I’m glad you asked!” he said, making Rei feel like he should not be glad at all. Nagisa pulled a key from his pocket. He twirled it around his forefinger. “This weekend a certain professor is going to visit their mother’s an won’t be around their boat.”

“Nagisa!”  
“What she won’t know won’t hurt her,” he defended, and enforced by sticking his tongue out.

“Do you even know how to drive a boat?”

“I have a whole week to figure out how.”

Rei groaned. 

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Rei bit his lip as Nagisa tossed a bucket into the trunk of his car. Binoculars, nets, and devices designed to measure salinity and temperature rattled inside. Nagisa chatted animatedly as he haphazardly threw in their jackets on top, along with a large bag of…something.

“What is that?” Rei asked, daring to peek at the contents. He pulled back with a curled lip at the dead eyes that gave him a glassy stare. “Fish?”

Nagisa nodded, grinning. “There’s shrimp in there too. Shrimp, tuna, mackerel, and some kind of frog.” He’s smile drooped as he caught Rei’s raised eyebrows. “Food might make them come out, but we don’t know what they like to eat. So we have to try a bunch of stuff first! Come on.” He slammed the trunk shut.

Rei slid into the driver’s seat and cleared his throat as he started the engine. Though he hated to dim Nagisa’s bright smile, the unease that filled his stomach was starting to hurt him more than the predicted pain of an unhappy man. “You should be prepared not to see them,” he began, hesitantly.

“What?” Nagisa asked, breaking off from his one-sided chatter about his classes. 

“I just mean, I don’t think you should get your hopes so high on another sighting.”

“You still don’t think they’re real,” the blond muttered. He crossed his arms. 

“Maybe the whole reason people think they don’t exist is because they’re very hard to spot. One sighting in a lifetime might be a chance that will never happen again. The one you saw – if it was what you say it is – could have just been passing through.”

“But that’s what the food is for, Rei. To get its attention.”

Rei sighed, dropping his shoulders, resigned. It was hard to argue with Nagisa’s logic after he was intent on doing something. “We can’t spend all day here,” he finished as they pulled up to the docks. 

Nagisa agreed with a small hum and jumped out of the car, hopping around to the trunk. He led Rei to the boat, Nagisa complaining on the slow pace Rei set while Rei complained of the weight of the tub he was forced to carry himself. They set up the equipment, took initial readings, and started the small boat. Rei paled after the first few jerky attempts to maneuver the ship out of the harbor, but soon Nagisa had it cutting smoothing through the rolling waves. 

“I think this is where we were last time,” Nagisa said, slowing down the boat so it glided around a pile of rocks. He opened the tub and began rummaging through the bags of fish. “I guess we’ll just wait now.”

Rei watched him start tossing the food into the water, a small frown on his face. Reluctantly, and with some prompting from Nagisa, he also began tossing some of the shrimp over the side of the boat as well. Seabirds dived to pick up the scraps that seals missed. Fish darted to the surface to pluck at the meat, but there were no signs of anything human. 

“Do you think they just don’t like these kinds?” Nagisa asked, crossing his arms as he watched Rei tip the last of the bag’s contents into the water. Bits of crab and leftover mackerel floated by the hull. “We could get something different next time.”

“I don’t think there should be a next time,” Rei sighed. He packed up the tub, starting to put everything away. 

“We still have tomorrow with the boat!” the blond whined.

“We’ve been out here for hours. Someone will find the boat gone, that the professor wasn’t here, and put two and two together. And I was already against the whole idea. I knew they wouldn’t be back.”

“But Rei-“

“Nagisa, please.” 

Nagisa turned with a huff but started to pick up their things. When he drove the boat back, his eyes kept roaming the water for any sign of the mermen, gripping the wheel tight in his need to prove that they existed. By the time Rei finished docking the boat, his knuckles were white, his palms were sweating, and he had found nothing. He dragged his feet up to dry land. 

“I will find them,” he mumbled to himself. He would prove that he had seen the merman, that they existed and that Rei was wrong. And he would do it himself next time. Because there would be a next time. 

At the rock outcropping, small fish were still bobbing near the surface, on the look-out for any more falling food. A shadow passed underneath them and they scattered, following the quick turn of one of their numbers that had seen the movement. A hand reached for the leftover mackerel the smaller fish had not been able to grab onto with their smaller mouths. The fish dipped underwater with a low ‘plop’.


	3. Chapter 3

**Summary for the Chapter:**

> If Rei doesn't believe in Nagisa, he'll just have to find proof on his own.

**Notes for the Chapter:**

> Eesh, this is really late, isn't it? But I did warn that NaNo would prevent quick updates. Soon though, I'll be able to put my full attention to this fic.

Nagisa frowned as the search results scrolled down his laptop screen. Though the time range was what he asked for, the price ranges were much higher than he had wished for. He let out a breath. He guessed that was what happened when people tried to rent kayaks in the middle of autumn. 

“What are you researching?” 

Nagisa jumped as Rei slid into the empty bench space next to him. He quickly shut his computer closed and forced a bright smile to his face. “Rei! It was warm for a change, so I thought I could do some homework outside.”

Rei nodded absentmindedly and glanced at the sky. Nagisa followed his gaze and his smile became more genuine. It was a nice day now that he thought about it. The sun wasn’t obscured by clouds and the clouds that were in the light blue sky were thin and white. 

“Do you want to do something this weekend? W-with me,” Rei clarified when the other man turned his attention to him. 

Nagisa’s lips curled up into an expression that made Rei shudder. “What kind of thing?”

“I don’t know if I want to ask you now. That look always scares me and I have no idea what you think about when you look like that except something goes wrong. For me. You seem to have a lovely time. I just want to see a movie with you.”

Nagisa laughed. “I would like to go out with you, but I have my own plans.”

Rei raised an eyebrow. “Oh?”

“I have some projects I have to catch up on and I should get to those before the professors get tired of pushing back the due date.” He looked away with a shoulder shrug as Rei’s eyes turned an icy blue. 

“You’ll never graduate in time if you keep this up.”

“But that’s why I have Rei! To copy my homework off of!”

“And then you’ll graduate without knowing anything,” Rei told him, looking at him with exasperation. “How will you ever get a job?”

“I’ll just follow you to where you go and keep copying you,” Nagisa chuckled.

Rei shook his head before checking his watch. “My next class is soon. We will do something over the weekend?”

“Sure,” the blond chirped. He waited for the other to enter the library nearby before opening his laptop again and clicking the link to the closest match for kayak rentals.

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Nagisa dropped the kayak onto the sand and placed his hands on knees while he caught his breath. In the early morning, the beach was foggy and empty. Nagisa had begrudgingly crawled out of the comfortable heat of his bed just after dawn to head to the bay to make sure no one would follow him here. He had picked up the boat the day before and had packed all he thought he needed. As he pushed the kayak into the swash, he double checked that that the binoculars, notepads, and bags of bait were strapped in tight. He jumped in and buckled himself in.

He paddled about the bay while tossing the bits of fish about him, attracting birds and large fish, but amongst all the flurry of activity, not once did the dolphin-like tail break the surface. He groaned when, after his supply of food was finished, he realized he had set everything up for nothing a second time. 

“You can’t scientifically say there’s no such thing as a merman since there is no proof of one,” he told himself,” because you also don’t have any proof that they don’t exist.” He sighed to himself and pulled his paddle out. “One more sweep of where we say him the first time and I’ll go home. Rei was right,” he said, pouting. 

He pushed the kayak across the water to the grouping of rocks where their seal counting lab had taken place. The fog had cleared hours before and he could see them from where he was. He could also see a person floating around them. Or, what looked like a person from the torso up. He took out his binoculars and laughed when he made up the familiar features of the man he had been looking for. He slowed his advance and let the currents push him further towards the rocks.

“Just a little closer…” Nagisa pressed himself as close to the edge of the kayak as he could. His tongue peeked through his lips as he concentrated on focusing the binoculars without losing his position. “Closer, come on.” He could see the speck of gray further off. “You can do it, come a little- Ah!”

His words ended in a shriek as he leaned too far forward for the tiny, one-man boat to balance and he fell over as it tipped and rolled. The papers and gear in his lap were carried away with the currents and his breath followed them, gone from him with a shocked gasp as his clothes filled with cold water and assaulted his nose and eyes. Nagisa’s chest burned and he fought to push himself out of the kayak.

The lack of water penetrating the waters of the bay wasn’t the only cause of his darkening vision. He flailed as he kicked his shoes off and pulled his jacket over his head to make himself lighter, but when he looked up to find the surface, his face fell. The fire in his chest told him he wouldn’t be able to make it to fresh air in time.

Rei would be very sad when he found out, he thought as he saw a flash of white. He closed his eyes and pursed his lips as it neared. He waited for the – he wasn’t exactly sure what he was supposed to wait for, but he was certain he wasn’t supposed to continue feeling cold and wet. Something bumped into him and wrapped itself around his waist and he jerked. He was certain he shouldn’t feel that.

The hold tightened and he cried out, only to suck water in. His eyes flew open when a hand slapped over his mouth before he could cough and draw more water into his lungs. They widened further, hurting now from the display of shock, and he lost his breath again, earning a disgruntled look from the man holding him. The dark hair that framed his blue eyes made Nagisa look down and he found the tail that was cutting through the water. Merman. 

Nagisa was sure his chest would explode, but from the pressure of his need for air or the excitement of being so close to the merman that welled in his heart he wasn’t sure. When his head finally broke through the surface, he had to be prompted to inhale. 

“You’re real,” he rasped after gaining control of his lungs. Water trickled from the corners of his mouth. He rubbed his eyes and wiped the bangs plastered from his face to see better see the somber eyes still watching him. The merman’s lips pressed into a line and he cocked his head when all Nagisa did was gape and blink. The man shook his head and his jaw dropped further when the other shoved him and barked out a guttural sound. “No, no, I’m okay! Thank you.” The expression didn’t change, but his eyes softened. 

Nagisa sighed wistfully. All the notes he could- “My notes!” Nagisa splashed the water in frustration and he whined. “Wait, come back!” he shouted when he lost sight of the merman. His dorsal fin broke the surface only a couple of feet away and his head appeared a minute later. It blinked at him. “I don’t know if you understand me, but we can find you again, right? I think Rei would get mad if I didn’t at least try to ask permission. I want to show him you exist! Okay?”

The merman barked again and dived, slapping the water hard with its flukes. Nagisa waited another minute before he was sure he wouldn’t resurface and started to swim to shore, trying hard to repeat everything in his mind to put on paper later.


End file.
